Triazine derivatives described in International Laid-open Publication WO90/09378 to Applicant are safe to gramineous crops, rice in particular, in both post-emergence treatment and pre-emergence treatment and exhibit high herbicidal efficacy against weeds which are hard to control. The general formula of the basic structure of the triazine derivative described in the above Publication is as follows. ##STR2## wherein X.sup.1 is methyl, trifluoromethyl, methoxy or a fluorine atom, n is an integer of 0, 1 or 2, and R.sup.1 is haloalkyl.
The above herbicides having high crops-weeds selectivity can control weeds without causing phytotoxicity on crops in general use, while they sometimes cause phytotoxicity due to various factors such as weather, environment and erroneous use. In particular, growth-inhibiting (particularly, root-inhibiting) herbicides are liable to cause phytotoxicity under conditions of an excessive water content. It is therefore desired to develop a herbicide which can control weeds without causing phytotoxicity on crops under such bad conditions and which have higher crops-weeds selectivity.
It is an object of the present invention to develop a novel triazine derivative having high crops-seeds selectivity under bad conditions such as conditions of an excessive water content which are liable to induce phytotoxicity, i.e., having safety to gramineous crops under conditions which are liable to induce phytotoxicity and having high herbicidal efficacy against weeds which are hard to control.